SUPPORTING INFORMATION
Studies on CH3CN-assisted decomposition of 1st Grubbs catalyst by
electrospray ionization tandem mass spectrometry
Zhi-Xiong Zhao, Hao-Yang Wang* and Yin-Long Guo*
Shanghai Mass Spectrometry Center, Shanghai Institute of Organic Chemistry, Chinese
Academy of Sciences, 345 Lingling Road, Shanghai 200032, P.R. China
*Correspondence to: H.-Y. Wang and Y.-L. Guo, Shanghai Mass Spectrometry Center,
Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road,
Shanghai 200032, P.R. China.
E-mail: haoyangwang@mail.sioc.ac.cn, ylguo@mail.sioc.ac.cn
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1. ESI mass spectra of Grubbs 1st catalyst in CH2Cl2
Figure S1. ESI-MS spectrum of 1 in CH2Cl2.
Figure S2. ESI-MS/MS spectra of the ions at: (a) m/z 822; (b) m/z 821.
Figure S3. ESI-MS/MS spectra of the ions: (a)(HPCy3)+ at m/z 281; (b)(PhCH2PCy3)+ at m/z
371.
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2. ESI mass spectra of Grubbs 1st catalyst in CH2Cl2 with CH3CN
Scheme S1. Equilibrium of Ru-complex ions in solution of completely decomposed 1 in the
presence of CH3CN.
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Figure S4. ESI-MS/MS of the ions at: (a) m/z 499; (b) m/z 540; (c) m/z 581; (d) m/z
820.
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Scheme S2. Proposed fragmentation pathway of the ion at m/z 499 in ESI-MS/MS.
In the ESI-MS/MS of the ion at m/z 499 (Fig. S4-a), the main product ion was that at
m/z 463 formed by loss of HCl. The ion at m/z 461 formed by loss of 2H from the ion
at m/z 463 could also be observed unambiguously, implying that dehydrogenation of
the ion at m/z 499 in MS/MS process. After dissociation of CH3CN from the ion at
m/z 463, the ion at m/z 420 and 418 formed by dehydrogenation could also be
detected. In the ESI-MS/MS spectra of the ion at m/z 820 (Fig. S4-d),
dehydrogenation also occurred when the product ion at m/z 738 fragmented to m/z
695 via loss of CH3CN plus 2H. The only origin of the hydrogen is the cyclohexyl
group in the phosphine ligand and C-H activation plays an important part in the
fragmentation process. This fragmentation involving C-H activation was also
observed in the MS/MS of the ion at m/z 507.
The first step of this process may be caused by the agostic interaction between
the ruthenium and the C-H bond in the phosphine ligand.1-2 Despite the many reports
regarding the agostic interaction and C-H bond activation between the ruthenium
center and the C-H bond in the NHC ligand of the 2nd-Grubbs catalyst, reports on
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interactions between the ruthenium and the C-H bond in the phosphine ligand of the
1st-Grubbs catalyst were limited. However, Placa and Ibers have reported the agostic
interaction in RuCl2[(PPh3)3] and Kubas also confirmed the agostic interaction in
M(CO)3(PCy3)2 (M=W, Mo or Cr) by their X-ray structures.3-6 Chaudret and
coworkers reported the dehydrogenation of a cyclohexyl group to form
[Cp*Ru(C6H9PCy2)]BF4 and [RuH{(μ3-C6H8)PCy2}{(μ2-C6H9)PCy2}].7-11 Thus, we
believe that agostic interaction and C-H bond activation play an important part in this
process.
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3. ESI mass spectra of 1 in CH2Cl2 mixed with CH3CN by microreactor
Figure S5. ESI-MS/MS spectra of the ions at: (a) m/z 507; (b) m/z 548; (c) m/z 589;
(d) m/z 787; (e) m/z 828.
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Scheme S3. Equilibrium of Ru-intermediate ions in solution of CH3CN-assisted
decomposition of 1st Grubbs catalyst 1 at the beginning stage of reaction within 26S.
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Figure S6. ESI-MS/MS of the ions at: (a) m/z 538; (b) m/z 497; (c) m/z 456.
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4. GC/MS studies on the decomposed solution of 1 with CH3CN
Figure S7. Detection of toluene in decomposed solution of 1 by GC/MS. (a)
Extracted ion spectrum for the ion at m/z 92; (b) EI-MS spectrum at 3.2 min.
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Figure S8. Expanded GC spectra for decomposed solution of 1: (1) expanded GC
spectrum at the base peak; (2–6) extractive ion spectrum for the ions at: (2) m/z 280;
(3) m/z 278; (4) m/z 276; (5) m/z 274; (6) m/z 262.
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Figure S9. GC-EI-MS spectra of the phosphines in the solution of completely
decomposed 1: (a) P(Cy)2Ph at 11.17 min; (b) P(Cy)2(C6H9) at 11.24 min; (c) PPh3 at
11.33 min; (d) PCy3 at 11.38 min.
The GC/MS results indicated that the main species in solution was still the PCy3 at
11.38 min with a molecular ion at m/z 280. Toluene was detected at the retention time
2.91 min with its molecular ion at m/z 92. Three small peaks were also detected near
the retention time of tricyclohexylphosphine. From their EI-MS spectra and the
extractive ion spectra, we identified them as PCy2Ph at 11.17 min, PCy2 (C6H9) at
11.24 min and P(Ph)3 at 11.33 min. Triphenylphosphine might come from the residue
during the preparation of Grubbs 1st catalyst, which is also detected in the control
experiment. P(Cy)2Ph and P(Cy)2(C6H9) were not detected in the control experiments,
and they might be formed via C-H activation on the phosphine ligand of PCy3 in the
Grubbs 1st catalyst by loss of one or three H2 molecules. The proposed formation
mechanism for these minor compounds is shown in Scheme S3.
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Scheme S4. Proposed C-H activation mechanism of phosphine PCy3 and its H2 loss
process.
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